The present invention relates to an image processing apparatus and method for exposing an intended image on an imaging drum to form a pre-press proof used in the printing industry but not limited to, and, more particular, to an image processing apparatus incorporating an imaging drum having automatic balance correction.
Pre-press proofing is a procedure that is used mainly by the printing industry for creating representative images of printed material without the cost and time required to produce printing plates and set up a high-speed, high volume, printing press to produce an example of an intended image. An intended image may require several corrections and be reproduced several times to satisfy or meet, customers requirements resulting in higher costs and a loss of profits which ultimately would be passed onto the customer.
One such commercially available image processing apparatus is arranged to form an intended image on a sheet of print media. Colorant is transferred, from a sheet of donor material to the print media by applying a sufficient amount of energy to the donor sheet material to form an intended image on the print media. The above mentioned image processing apparatus generally includes a material supply assembly or carousel, and a lathe bed scanning subsystem or write engine, which includes a lathe bed scanning frame, translation drive, translation stage member, printhead, load roller, imaging drum, print media exit transport, and dye donor sheet material exit transport.
Operation of the image processing apparatus generally includes metering a length of the print media (in roll form) from the material assembly or carousel. The print media is then cut into sheet form of the required length and transported to the imaging drum. It is then wrapped around and secured onto the imaging drum. A load roller, which is also known as a squeegee roller, aids in removing any entrained air between the imaging drum and the print media. Next, a length of donor material (in roll form) is metered out of the material supply assembly or carousel, and cut into sheet form of the required length. It is then transported to the imaging drum and wrapped around the periphery of the imaging drum. The load roller removes any air entrained between the imaging drum, print media, and the donor sheet material. The donor sheet material is superposed in the desired registration with respect to the print media, which has already been secured to the imaging drum.
After the donor sheet material is secured to the periphery of the imaging drum, the scanning subsystem or write engine, provides the scanning function. This is accomplished by retaining the print media and the donor sheet material on the imaging drum while it is rotated past the printhead as the translation drive traverses both the printhead and translation stage member axially along the axis of the imaging drum in coordinated motion with the rotating imaging drum. These movements combine to produce the intended image on the print media.
After an intended image has been formed on the print media, the donor sheet material is removed from the imaging drum without disturbing the print media beneath it. The donor sheet material is then transported out of the image processing apparatus to a waste bin. Additional donor sheet materials are sequentially superimposed with the print media on the imaging drum, further producing an intended image. With the completed intended image formed on the print media it is then unloaded from the imaging drum and transported to an external holding tray on the image processing apparatus.
Although the presently known and utilized image processing apparatus is satisfactory, a need exists to allow for self-balancing correction of an imaging drum during rotation with different sizes of media.
A self-balancing image processing apparatus for writing intended images to print media comprises a self-balancing imaging drum having an external surface with a plurality of vacuum holes for supporting the print media. A printhead forms an intended image on the print media. A drive motor rotates the self-balancing imaging drum. A blower creates a first vacuum supply to the self-balancing imaging drum for holding the print media on the external surface of the self-balancing imaging drum. At least one balance corrector consists of a vacuum cylinder for housing a vacuum piston with a return spring mounted in the wall of the self-balancing imaging drum, for creating a second vacuum supply to the external surface for holding the print media. The balance corrector is adapted to allow the vacuum piston to move outwardly to compensate for the lack of print media on the external surface of the self-balancing imaging drum thus correcting the balance of the self-balancing imaging drum. In the most preferred embodiment, the self-balancing imaging drum has a large number of balance correctors disposed in the wall of the self-balancing imaging drum.
A method for loading and unloading print media from a self-balancing imaging drum comprises creating a first vacuum supply in a hollowed-out interior portion. The self-balancing imaging drum having an external surface with a plurality of vacuum holes communicates with the first vacuum supply within the hollowed-out interior portion the of the self-balancing imaging drum. The print media is loaded on the external surface of the self-balancing imaging drum. The print media is held on the external surface by means of a vacuum drawn through the plurality of vacuum holes on the external surface. The self-balancing imaging drum is rotated forming a second vacuum supply to the external surface of the self-balancing imaging drum during rotation using at least one balance corrector consisting of a vacuum cylinder for housing a vacuum piston with a return spring mounted in the wall of the self-balancing imaging drum. If no print media is disposed over at least one of the balance correctors, the balance corrector allows a vacuum piston to move outwardly to compensate for the lack of print media on the external surface of the self-balancing imaging drum correcting the balance of the self-balancing imaging drum.
In the operation of the invention, it is contemplated that the vacuum level of the first vacuum supply may be varied using a vacuum supply controller. For the second vacuum supply it is contemplated that it could also be varied with a vacuum supply controller, but more preferably the second vacuum supply is varied with the rotational speed of the self-balancing imaging drum, and no additional equipment is needed, reducing the expense of the equipment. If a vacuum supply controller is used, it is contemplated that the vacuum supply controller can vary the speed of the blower by pulse width modulation of the DC voltage level to the blower.
A self-balancing imaging drum for supporting print media comprises an external surface having a plurality of vacuum holes extending from the hollowed-out interior portion of the self-balancing imaging drum. A first vacuum supply is formed in the hollowed-out interior portion thereby communicating vacuum through the plurality of vacuum holes for holding print media onto the external surface of the self-balancing imaging drum. At least one balance corrector consists of a vacuum cylinder for housing a vacuum piston with a return spring mounted in the wall of the self-balancing imaging drum such that when the self-balancing imaging drum is rotated it generates a second vacuum supply to the external surface of the self-balancing imaging drum for holding the print media. If no print media is present the vacuum piston moves outwardly to correct the balance of the self-balancing imaging drum. In the most preferred embodiment, the self-balancing imaging drum has a large number of balance correctors disposed in the wall of the self-balancing imaging drum.
A self-balancing imaging drum for supporting print media comprises an external surface having a plurality of vacuum holes extending from the hollowed-out interior portion of the self-balancing imaging drum. A first vacuum supply is formed in the hollowed-out interior portion thereby communicating vacuum through the plurality of vacuum holes for holding print media onto the external surface of the self-balancing imaging drum. At least one balance corrector consists of a vacuum cylinder for housing a balancing ring with a return spring mounted in the wall of the self-balancing imaging drum such that when the self-balancing imaging drum is rotated, if no print media is present, the balancing ring moves outwardly to correct the balance of the self-balancing imaging drum and further the balancing ring blocks the vacuum passage to the first vacuum supply thus increasing the efficiency of the first vacuum supply. In the most preferred embodiment, the self-balancing imaging drum has a large number of balance correctors disposed in the wall of the self-balancing imaging drum.